A discussion of the relativistic formulation of the deuteron-nucleus interaction at intermediate energies using the impulse approximation and the Bethe-Salpeter formalism is presented. By folding nucleon-nucleus Dirac interactions with different models of relativistic deuteron bound state wave functions we find that the strength of the effective deuteron spin-orbit potential depends crucially on the correct description of the initial and final state momenta of the individual nucleons. The model consistent with the diagrams of the impulse approximation predicts a spin-orbit strength in qualitative agreement with the nonrelativistic deuteron folding model. Previous discrepancies between relativistic and nonrelativistic descriptions of the deuteron-nucleus interaction are resolved. This result is confirmed by a fully relativistic calculation of the deuteron-nucleus T matrix based on the impulse approximation which uses a Bethe-Salpeter wave function for the deuteron.